By Warren Miller, contributing writer
Car batteries are one of those things that we just want to have work — with no hassle or worry. You don't want to have to open the hood and check on your battery every week, month, or even year. You just want it to work reliably in any environment. It might surprise you that not all car batteries can actually provide the level and reliability and consistency that you might expect. It probably won't surprise you, however, that you might need to pay a bit more for higher reliability and confidence.
Lead-acid batteries
Car batteries have a very simple job to do. They need to provide enough power to start the car. The most common type of car battery is the wet/flooded lead-acid battery, and starting the car normally uses only about 3% of the lead-acid battery’s charge, so there is plenty of energy available. Lead-acid batteries use a very simple chemical process to generate current. As the name implies, these batteries use a combination of lead plates and liquid sulfuric acid. The acid reacts with the lead dioxide coating on the plates to produce lead sulfate and free electrons, thus creating the battery’s current. By applying current to the battery, the lead sulfate is converted back to lead dioxide.
Drawbacks
These types of batteries are inexpensive to make and effective, but they do have one key drawback. A deep discharge can cause the plates to be coated with a thick layer of sulfate, which inhibits the normal chemical process. This can dramatically reduce the battery’s ability to provide current and can eventually result in a “dead” battery. “Jumping” it may get the car started again, but if it isn’t being recharged, you will still have a dead battery the next time you start up the car.
Supply chain — are you sure you know where it came from?
Another issue faced by normal car batteries comes from the supply chain. How can you know for sure if the battery you are buying is new and not recycled or used? You have probably seen signs at your local gas station or auto repair place that they will buy used batteries. These aren’t going into a landfill. They are being recycled and re-used, which is a good thing, but not if you don't know that you are getting a refurbished battery. Making sure that you get a warranty on your new battery is one way that you can protect yourself, but it might not provide much solace if your battery fails on a cold winter night.
The future could be in absorbent glass mat
Other battery technologies are emerging that could help improve the situation. Absorbent glass mat (AGM) batteries contain the active electrolyte in glass mats instead of freely floating around the plates. This reduces the deep-discharge effect of over-coating the plates and also reduces leakage that deteriorates battery effectiveness and may damage parts of the engine. These batteries only cost a bit more than lead-acid batteries, so perhaps they will become a more popular alternative in the coming years.
Lithium-ion vs. lead-acid
Another battery technology, lithium-ion, has several advantages over lead-acid batteries. They weigh much less — around 30% of a lead-acid battery. They also have higher efficiency because they provide 100% of their total capacity, while lead-acid batteries only provide around 30% of their total capacity. They are also less affected by deep-discharge events because the electrolyte composition is independent of its charged state. Lithium-ion batteries can cost 10 times as much as a lead-acid battery, however, so they are not expected to replace the common lead-acid battery any time soon.
If you stick with the current battery leader, lead-acid, it’s probably a good idea to make sure you are getting a new one, not a refurbished one. Even if it has been tested and is advertised as ”good as new,” you just can’t tell the discharge history of the battery from the outside — and you don't want to open it up to have a look because that could create an even bigger problem than a dead battery in a snowstorm.
Source: Electronics360
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